The Republican. [volume] (Oakland, Md.) 1877-current, 1887-03-26

increased in splendor till 1t rlvaled
Venus, and was quite visible at noon
day. 1t began to fade in the following
month, and in March Of 1873, though
] then very much fainter than when dis
covered, it was still fair first-magni-
tude star, being as bright as Aide
baran, the most brilliant luminary in
| the constellation of the Bull. During
| the next twelve months it gradually
faded, till at length it became quite in
visible. No star can now be seen in
the position referred to as occupied by
| it; but some years ago, a minute star
was discovered near its place, and
where one was not hitherto known.
| From the fact that stars of a SINH
lar character to that of 1872 are
reported to have appeared in an
approximate position in the years 945
and 1864, some astronomers would have
us believe that variable star having a
period of somewhat over three hundred
years exists in this part of the heavens.
If so, we may not have long to wait for
another apparition of this most remark
able object. 1t should, however, be
borne in mind that if the star appeared
as suddenly as Tycho would lead us to
believe, there is great improbability
that it is periodically variable.
Thirty years after the disappearance
of this object, another star blazed out
in the constellation of Serpentarius and
remained visible for about three
months 1t is said to have rivaled
| Tychos star in splendor; but as it was
not favorably situated for observation,
we have a very meager array of facts
concerning it. 1t is known as Kepler's
star, having been described to us by
that astronomer.
Passing over the apparition of one or
two stars too unimportant to be noticed,
we come now to the temporary stars of
modern times. Here we have great
advantage over the old astronomers,
for they, in dealing with temporary
stars, could record only their brilliancy,
duration of visibility, and facts of a
similar kind; but since their time we
have had placed in our hands the tele-
scope and the spectroscope, the former
enabling us to watch a star long after
it becomes invisible to the naked eye;
the latter giving us valuable information
on the changes in progress in its physical
constitution. Both of these instruments
have been employed with success in
observing the temporary stars of recent
times, and especially is this the case, as
regards the spectroscope at least, in
the observation of the star which APP
peared in 1866 in the constellation of
the Northern Crown, and which is
technically known as the Blaze Star.
The Blaze Star was not, strictly speak
| ing, a new one, as it was already
| known to astronomers. The younger
Herschel in 1912 gave it as of the sixth
magnitude; and Argelander in 1866
noted it as about the t6nth-the object
in both cases being invisible to the
naked eye. We have therefore good
reason to believe that it was originally
variable. However, in 1866 it suddenly
increased in splendor, and when first
noticed, on the 18th of May of that
year, was of the second magnitude. 1t
retained its splendor only very short
time, for on the oath of the same month
it was invisible to the naked eye. In
August it again revived slightly; but
since that time it has been irregularly
decreasing.
During all these fluctuations 1t was
carefully examined both with the tele-
scope and the spectroscope, but espe-
cially with the latter. What then
did the spectroscope reveal regarding
it? 1t revealed beyond doubt that
the sudden increase in brilliancy was
caused by an intense glowing of the
hydrogen gas existing in the vaporous
envelope surrounding the star. All
stars are surrounded by an envelope
consisting of the vapors of the materials
though not necessarily of all the ma
terials-of which the stars themselves
are composed. These vapors. though
intensely hot, are cool when compared
with the intenser heat of the star itself
they therefore absorb more light and
heat than they emit, and when the
light of a. star is examined with
a spectroscope, this absorption
makes itself known in the long, mar
row, rainbow-colored band known as
the spectrum, by the presence of delicate
dark lines or gaps which are perpen-
dicular to the length of the spectrum
and which indicate that certain definite
part of the light is absent. Each vapol
has in any given spectrum its own
characteristic dark lines. But the
hydrogen lines in the spectrum of the
Blaze Star, instead of being dark, were
bright. In fact, the whole extra light
of the star seemed concentrated in foul
bright lines, which were referred to the
elements nitrogen and hydrogen. The
brightness of these lines indicated that
from some unknown cause, the hydrogen
gas existing in the vaporous envelope
of the Blaze Star had become so in
tensely heated that it burst out in ;
sudden excess of light, which, to us
converted the star from a faint to ;
] I